Anth Sdk Patterns

---
name: anth-sdk-patterns
description: "'Apply production-ready Anthropic SDK patterns for TypeScript and Python. Use when implementing Claude integrations, building reusable wrappers, or establishing team coding standards for the Messages API. Trigger with phrases like \"anthropic SDK patterns\", \"claude best practices\", \"anthropic code patterns\", \"production claude code\". '"
allowed-tools: "Read, Write, Edit"
category: ai-agents-and-harness
source_repo: jeremylongshore/claude-code-plugins-plus-skills
source_path: "plugins/saas-packs/anthropic-pack/skills/anth-sdk-patterns/SKILL.md"
source_url: https://github.com/jeremylongshore/claude-code-plugins-plus-skills/blob/HEAD/plugins/saas-packs/anthropic-pack/skills/anth-sdk-patterns/SKILL.md
---

# Anthropic SDK Patterns

## Overview

Production-ready patterns for the Anthropic SDK covering client management, error handling, type safety, and multi-tenant configurations.

## Prerequisites

- Completed `anth-install-auth` setup
- Familiarity with async/await patterns
- TypeScript 5+ or Python 3.10+

## Pattern 1: Typed Wrapper with Retry

```typescript
import Anthropic from '@anthropic-ai/sdk';
import type { Message, MessageCreateParams } from '@anthropic-ai/sdk/resources/messages';

class ClaudeService {
  private client: Anthropic;

  constructor(apiKey?: string) {
    this.client = new Anthropic({
      apiKey: apiKey || process.env.ANTHROPIC_API_KEY,
      maxRetries: 3,      // SDK handles 429 + 5xx automatically
      timeout: 60_000,
    });
  }

  async complete(
    prompt: string,
    options: Partial<MessageCreateParams> = {}
  ): Promise<string> {
    const message = await this.client.messages.create({
      model: options.model || 'claude-sonnet-4-20250514',
      max_tokens: options.max_tokens || 1024,
      messages: [{ role: 'user', content: prompt }],
      ...options,
    });

    const textBlock = message.content.find((b) => b.type === 'text');
    if (!textBlock || textBlock.type !== 'text') {
      throw new Error(`No text in response: ${message.stop_reason}`);
    }
    return textBlock.text;
  }

  async *stream(prompt: string, model = 'claude-sonnet-4-20250514'): AsyncGenerator<string> {
    const stream = this.client.messages.stream({
      model,
      max_tokens: 4096,
      messages: [{ role: 'user', content: prompt }],
    });

    for await (const event of stream) {
      if (event.type === 'content_block_delta' && event.delta.type === 'text_delta') {
        yield event.delta.text;
      }
    }
  }
}
```

## Pattern 2: Multi-Turn Conversation Manager

```python
import anthropic
from dataclasses import dataclass, field

@dataclass
class Conversation:
    client: anthropic.Anthropic = field(default_factory=anthropic.Anthropic)
    model: str = "claude-sonnet-4-20250514"
    system: str = ""
    messages: list = field(default_factory=list)
    max_tokens: int = 4096

    def say(self, user_message: str) -> str:
        self.messages.append({"role": "user", "content": user_message})

        response = self.client.messages.create(
            model=self.model,
            max_tokens=self.max_tokens,
            system=self.system,
            messages=self.messages,
        )

        assistant_text = response.content[0].text
        self.messages.append({"role": "assistant", "content": assistant_text})
        return assistant_text

    @property
    def token_count(self) -> int:
        """Estimate total tokens in conversation."""
        return sum(len(str(m["content"])) // 4 for m in self.messages)

# Usage
conv = Conversation(system="You are a helpful coding assistant.")
print(conv.say("What is a closure in JavaScript?"))
print(conv.say("Can you show me an example?"))  # Has full context
```

## Pattern 3: Structured Output with Prefill

```python
import json
import anthropic

client = anthropic.Anthropic()

def extract_structured(text: str, schema_description: str) -> dict:
    """Force JSON output using assistant prefill technique."""
    message = client.messages.create(
        model="claude-sonnet-4-20250514",
        max_tokens=1024,
        messages=[
            {"role": "user", "content": f"Extract data from this text as JSON.\n\nSchema: {schema_description}\n\nText: {text}"},
            {"role": "assistant", "content": "{"}  # Prefill forces JSON output
        ]
    )
    json_str = "{" + message.content[0].text
    return json.loads(json_str)

# Usage
data = extract_structured(
    "John Smith, 35, lives in NYC and works at Google as a PM.",
    '{"name": str, "age": int, "city": str, "company": str, "role": str}'
)
# {"name": "John Smith", "age": 35, "city": "NYC", "company": "Google", "role": "PM"}
```

## Pattern 4: Multi-Tenant Client Factory

```typescript
const clients = new Map<string, Anthropic>();

export function getClientForTenant(tenantId: string): Anthropic {
  if (!clients.has(tenantId)) {
    const apiKey = getApiKeyForTenant(tenantId);  // From your secret store
    clients.set(tenantId, new Anthropic({ apiKey }));
  }
  return clients.get(tenantId)!;
}
```

## Pattern 5: Token-Aware Request Sizing

```python
# Use the Token Counting API to pre-check request size
count = client.messages.count_tokens(
    model="claude-sonnet-4-20250514",
    messages=[{"role": "user", "content": long_document}],
    system="You are a summarizer."
)
print(f"Input will use {count.input_tokens} tokens")

# Adjust max_tokens to stay within budget
remaining_budget = 200_000 - count.input_tokens
max_tokens = min(4096, remaining_budget)
```

## Error Handling

| Pattern | Use Case | Benefit |
|---------|----------|---------|
| SDK `maxRetries` | 429 / 5xx errors | Built-in exponential backoff |
| Prefill technique | Force JSON output | No regex parsing needed |
| Token counting | Long documents | Prevent context overflow |
| Client factory | Multi-tenant SaaS | Key isolation per customer |

## Resources

- [Client SDKs](https://docs.anthropic.com/en/api/client-sdks)
- [Token Counting API](https://docs.anthropic.com/en/docs/build-with-claude/token-counting)
- [Prompt Caching](https://docs.anthropic.com/en/docs/build-with-claude/prompt-caching)

## Next Steps

Apply patterns in `anth-core-workflow-a` for tool use workflows.

---

**Source:** [`jeremylongshore/claude-code-plugins-plus-skills`](https://github.com/jeremylongshore/claude-code-plugins-plus-skills) → `plugins/saas-packs/anthropic-pack/skills/anth-sdk-patterns/SKILL.md`